1. Field of the Invention
This invention generally relates to handling differing print element requirements. More specifically, this invention relates to expanding the usefulness of print elements in order to reduce print element change requirements and increase throughput.
2. Description of the Prior Art
With the advent of electronic keyboards in word processing systems, the ability to efficiently change keyboard coding to accommodate different print elements has been improved. Mechanical type changes are no longer required. An operator can now change from, for example, English keyboard coding to German keyboard coding by simply keying a keyboard coding change to the system.
There are two types of systems which are readily available in the marketplace today. One includes an interactive keyboard and printer, and the other includes an interactive keyboard and display. In the interactive keyboard/printer system, characters are printed as keyed. In both, keyed characters and keyboard coding changes are stored in a text buffer for later printout and control of printout. During printout at any time using prior art systems, a matching of keyboard coding and printer print elements is required to provide intelligible printed text. Such a requirement can result in an excessive number of print element changes. This is particularly the case when printing is to occur from a buffer and sequentially stored English and German columns are to be printed out in a side-by-side format.
In order to more fully appreciate the problems encountered with present day systems, it is to be recalled that each of the characters and/or graphics included on a print element exist at a particular location on the element. For a wide range of characters, the locations are the same on a wide variety of elements. For example, a lower case "a" will exist at the same location on many of the print elements available for a particular system. A change in keyboard coding presents no problem for this character as long as the character exists on the print element being used. On the other hand, there are certain characters which exist at different locations on different print elements. If the keyboard coding does not match the print element being used, a different character than that keyed will be printed, even though the keyed character is available on the element. With the instant invention, there is in essence a recoding to cause the intended character to be printed from the print element. There are other instances where a composite character such as, for example, an overstruck "a" (a) is called for by the keyboard coding. This composite character is not available as a single character on a wide range of elements, but both the overstrike and lower case "a" characters are widely available on many elements. If both are available on the element in use, the character can be constructed according to this invention.
Representative of the closest known prior art related to reducing print element change requirements are U.S. Pat. Nos. 4,026,403 and 4,205,922. In the first mentioned patent, a reduction in print element change requirements is realized in that the most frequently used or needed characters are arranged on a first to be used print element. Using the first element, all characters capable of being printed are printed on a page and then a second print element is required. The second print element is then used to the extent possible to fill in unprinted areas on the page. If the entire page has not been printed, at least a third print element is required.
U.S. Pat. No. 4,205,922 addresses the problem of stored print element change requirements not corresponding to current printer requirements. That is, when text is stored sequentially, but printed out non-sequentially, a stored print element change requirement may not, in fact, require a change in elements. The disclosed system is structured to alert the operator only when changes are actually necessary.
In summary, the above described art is relevant to varying degrees, but falls short of either anticipating or rendering the instant invention obvious. More specifically, the instant invention presents an advance over the prior art in that sequentially called for print element changes are actually required and signalled only when the print element in use does not contain the next character to be printed and the next character to be printed cannot be constructed from the characters existing on the print element in use. Some of the more important advantages of this advance are (1) the flexibility of standard, readily available print elements is improved, and (2) actual print element change requirements are reduced.